How should Adolf Hitler engage to claim victory at the World War II?

The answer is obvious if you look at how that invasion had started.

Soviet Army was 3 times larger in troops, had much larger air force and huge number of tanks far superior than anything Germans had at that time. And that Army did not really fight. It dropped its equipment (including gasoline Germans badly needed to continue their progress) and ran to the east or surrendered to German platoons happened to walk by.

Soviet soldier hated Communists and saw absolutely no point to risk his life to protect Stalin's regime. Soviet officers were specifically selected by Stalin for their lack of courage and absence of any creativity. They could not rally and could not inspire their troops.

In its first year it was successful beyond the wildest German's dreams.

Obviously Hitler needed another year like that to defeat Stalin.

It means that whatever caused change in the level of Soviet fighting should not have happened.

What did happen?

Soviet soldier had realized that Nazi are worse than Communists and had started to fight Nazi for real. Germany had no resources to stand against USSR if Soviet Army really fights.

The brutality of the Nazi troops toward occupied local population and absolutely no desire to abolish the dreaded socialist collective farming had caused that change of hearts.

If Hitler would abolish collective farming and restored family farming system for Russians and if Nazi would give more respect to the local population, Hitler would win that campaign.

He thought the USSR was going to be so much of a pushover that he even had the invitations for the Victory Dinner at the Hotel Astoria in Leningrad printed up.

Don't know why you think it was 'unecessary'. Hitler knew he would have to beat Stalin at some point. (Don't be mislead by the Molotov-Ribbentrop agreement - a common mistake. Communist and Facists do not make good bedfellows - the pact was purely to give Hitler a free hand in Poland when it suited him). He reckoned he needed to attack sooner rather than later, given Stalin's pre-war decimation on the hierarchy of the Red Army which had left it in disarray (but not fatally so) - an underestimation given the resolve of the Russians to protct Mother Russia - and one that Napoleon had made before him.

His real tactical error was not to conclude matters in the west before attacking Russia (ie he should have defeated britain when he had the chance) so that he could prosecute Barbarossa unfettered - and also allowing Japan to dictate the agenda with the US which left him vulnerable to eventual attack from the Atlantic - or from the south when Rommel failed to control North Africa and he eventually lost the support of Italy.

They got here interior a hairs breath from defeating the Soviets. If Moscow could have fallen, there replaced right into a lot of area to maintain on the conflict, many of the conflict factories have been moved east and the Caucasus oil fields have been nonetheless of their administration. After the defeat in front of Moscow, the conflict replaced into nonetheless up for grabs. After Stalingrad, besides the fact that, the tip replaced into now no longer in doube.

After Hitler killed himself the party was pretty much over.